1. Field of the Invention
This invention relates to new and useful improvements in downhole motors and more particularly to bearing assemblies for use on downhole motors.
2. Brief Description of the Prior Art
Drilling apparatus wherein a drill bit is operated by a downhole motor, such as positive displacement fluid motors or a turbine driven motors, are well known in the prior art. In such motors, the drill bit is rotated by a rotor being turned by flow of fluid, such as drilling fluid through the motor assembly.
In such downhole motor assemblies, bearings are provided which are sometimes part of the overall motor assembly and which are sometimes provided in a separate bearing pack or bearing assembly which is fastened or secured to the motor housing. The bearings support the drilling thrust on the shaft during the drilling operation. Other bearings transfer hydraulic thrust from the motor to the shaft when the motor is pulled from the bore hole or when the drill bit is lifted off bottom.
Bearings assemblies are usually provided with springs to absorb axial shock loading during drilling. In most bearing assemblies, there are provided both axial thrust bearings and radial bearings. The thrust bearings may have to carry varying amounts of axial thrust depending upon the weight applied to the bit during the drilling operation. In some cases there is need to support a substantial amount of upward thrust. In other cases, more or less of equal amounts of upward and downward thrust need to be supported. In still other cases, there is a need for supporting downward thrust loads.
Tschirky U.S. Pat. No. 3,879,094 discloses a downhole motor consisting of a positive displacement motor having a bearing assembly on the motor housing which has tungsten carbide radial bearings and a plurality of longitudinally spaced axial thrust bearings.
Tiraspolsky U.S. Pat. No. 3,449,030 discloses a bearing assembly for use in downhole motors which includes a plurality of spaced axial thrust bearings having woven wire annular pads which function to absorb shock.
Garrison U.S. Pat. No. 3,594,106 discloses a downhole motor assembly having a plurality of longitudinally spaced axial thrust bearings and a spring mechanism for absorbing shock.
Stodt U.S. Pat. No. 4,135,772 discloses a bearing assembly for a downhole motor driven drill having axially spaced ball bearings for carrying axial thrust loads and having springs interposed between the bearings for absorbing shock.
Crase U.S. Pat. No. 4,260,202 discloses a bearing assembly for downhole motors which includes spaced ball bearing assemblies which include springs for absorbing axial shock.
Winkelmann U.S. Pat. No. 4,388,973 discloses a bearing assembly for a downhole motor in which bearings are spaced by shoulders on a series of sleeves which form a continuous supporting tube on the inside and outside of the bearing structure and supported on the rotating motor shaft. These bearings include springs for absorbing axial shock loads but are not constructed for interchangeability of the positioning of the bearings for determining the amount of upward and downward thrust supported by the bearing assembly.